This invention relates to conveyor systems and, in particular, mobile conveyor machines for use with endless conveyor belts and hitching apparatus for use with such machines and other mobile machines.
Belt conveyors are well known and are efficient means for moving large quantities of materials such as ore, coal and granular stone over a predetermined distance extending either horizontally, vertically or both. One form of conveyor system known for mining applications is a system involving a series of conveyors mounted on wheels so as to make the system easily movable. Because of the manner in which mines are developed and extended, it may be necessary for a relatively long conveyor system to be moved along a substantially curved or zig zag course. Under such circumstances, it can be difficult and time consuming to move the conveyor system when required. It will also be appreciated that it may be necessary to move the conveyor system and to make adjustments to the system fairly frequently as the mining machine advances in a mine.
U.S. Pat. No. 5,366,059 issued Nov. 22, 1994 to Prairie Machine & Parts Mfg. Ltd. describes and illustrates a conveyor system comprising a plurality of conveyor vehicles connected together in the form of a train and also describes a steering system for steering this train of vehicles. All but one of the vehicles in the train has a single pair of steerable wheels with the vehicle at the outby end of the train (that is the end to which the mine material is being delivered) having two steerable wheels. Hydraulic cylinders are used to steer each of the pairs of steerable wheels and there is a control mechanism for controlling and coordinating these cylinders in order to set the steering angles of the pairs of wheels. In this known system, each pair of wheels is mounted on an axle and each pair is driven by an electric tram motor mounted along the longitudinal centre of the conveyor vehicle. One difficulty encountered with this known conveyor system is that the system is relatively high along most of the length of the train and therefore the ceiling of the region of the mine where the mining machine is operating must be reasonably high, for example over six feet, to accommodate this conveyor system. Moreover, in this known system, the height of each pair of wheels relative to the conveyor frame is not adjustable.
There is a need in the belt conveyor industry to provide a hitching apparatus for pivotably connecting one end of a conveyor vehicle or conveyor machine to an adjacent end of another conveyor vehicle or conveyor machine. In particular, it is desirable to provide a new hitching apparatus which can be provided at one end of a conveyor machine that has a desirable low profile in order that the machine, as well as other machines connected thereto, can be used in areas of mines or mine shafts that have a relatively low ceiling, for example, a ceiling that is less than six feet. Such low ceiling mine areas and mine shafts are relatively common and it will be appreciated that often, from a mine economic standpoint, it may be too expensive to simply increase the ceiling height in order to accommodate a mobile conveyor system.
In addition, there is a perceived need to provide a reliable hitching apparatus for a mobile machine such as a mobile conveyor wherein the pivot point between two adjacent mobile machines or mobile conveyors is located between the pair of wheels located adjacent one end of one of the machines in order to enable the conveyor machines to be steered properly using an automated steering system for the conveyor system which is operated by an operator of the system.